The Radiofrequency Identification technology (RFID) has had a huge growth these last years, due to its versatility and the uncountable possibilities to integrate this technology in many different application (tracking and inventory of goods, access control, supply chain, etc.), and in particular the brand new context of internet of things projects. For some years, the near field UHF RFID applications has been developed in order to overcome the problems related to degradations of tag’s read range when needing to use it in a perturbing environment.The research work presented in this thesis come as a study of the UHF RFID in near field and far field zones. This study focus more particularly on the design of reader and tag antennas and on the characterization method in near field and far field zones. A study on the characteristics of fields outgoing from an antenna has been made, in order to underline the important criteria for the design of performant UHF RFID reader antennas in near field zone. From the state of art about tag antennas design and classical methodologies, we propose a new approach that aims improving the design of tag antennas in a more suitable point of view that is getting the expected power level in a given application. Finally, with an objective to characterize UHF RFID tags, we first propose a new approach enabling the identification of tag families, and then propose a new innovating power transfer efficiency measurement procedure, that has been validated experimentally.